This paper introduces the U.S. standard system for existing buildings， analyzes the seismic evaluation techniques， and focuses on the FEMA P-154-2015 rapid visual screening method and the ASCE/SEI 41-23 three-level evaluation process. The United States adopts a grading mode characterized by “graded screening， differentiated evaluation， and targeted reinforcement” for the governance of existing buildings. This mode offers the advantages of flexibility and high efficiency， while also having certain limitations. By comparing the standards of the two countries and considering China's actual conditions， this paper proposes recommendations， such as defining benchmark buildings to simplify the evaluation process and improving performance-based assessment methods to complement traditional appraisals. It aims to provide technical references for construction projects under “the Belt and Road” initiative， thereby offering insights for the scientific and standardized management of existing buildings as well as for urban renewal.

The Nanjing City Wall represents the pinnacle of ancient Chinese city wall construction and holds significant cultural heritage value. However， due to the deterioration of its structural integrity and external environmental factors， it faces substantial safety concerns requiring urgent restoration and reinforcement. First， this study examined the structural configuration and damage conditions of the section from Jiefang Gate to Xuanwu Gate based on field surveys and literature review. Second， finite element analysis using ANSYS software was conducted on the wall structure. The analysis focused on evaluating the mechanical properties and safety under various combined conditions， including the effects of air-raid shelters and moisture absorption/expansion of internal brick-rubble-soil fill， to identify potential hazards. Finally， adaptive restoration and conservation measures were proposed， balancing both the preservation of historical appearance and the reinforcement of structural safety. This study implemented targeted reinforcement measures for different types and grades of deterioration， including structural strengthening of wall bodies， rampart top surfaces， and arches. Under the premise of preserving historical appearance， the wall structure was reinforced to achieve minimal intervention conservation for cultural heritage buildings， providing valuable insights and references for the preservation and restoration of ancient city walls.

Efficient and reliable structural health monitoring is essential for ensuring the safety and extending the service life of steel structures. Owing to the advantages of non-contact nature， high efficiency， and a high degree of automation， computer vision （CV） has gradually become an important technology for the inspection and maintenance of steel structures. Focusing on surface cracks and corrosion damage of steel structures， this review systematically summarizes the recent research progress in CV-based damage detection and outlines the major approaches， including image classification， object detection， and image segmentation. Particular attention is paid to key optimization strategies for small object detection， robustness under complex backgrounds， few-shot learning， and on-site deployment. Existing studies indicate that CV has significantly improved the automation， intelligence， and precision of damage detection for steel structures. However， further advances are still required in dataset standardization， model robustness to interference， generalization capability across scenarios， and lightweight real-time inference.

Dovetail profiled steel sheets are characterized by a unique rib configuration that ensures a flat plate surface. Compared with conventional flat steel plates， they offer higher buckling resistance， greater out-of-plane stiffness， and more effective interaction with concrete. These superior properties render them well-suited for enhancing the mechanical properties of wall claddings， lateral force-resisting components， and steel-concrete composite structures. To clarify their in-plane shear mechanism， pure shear diagonal loading tests were conducted on two dovetail profiled steel sheet specimens： DPS-V with vertically oriented ribs and DPS-D with ribs inclined at 45°. Experimental observations were focused on buckling modes， deformation evolution， and failure modes， while finite element analysis （FEA） was employed to further elucidate the underlying working mechanism. The results indicated that the profiled ribs provided effective boundary restraint to the plate strips， thereby inhibiting global penetrating buckling. Both specimens exhibited localized buckling within the plate strips， with DPS-V undergoing shear buckling and DPS-D experiencing compressive buckling. Owing to the boundary restraint provided by the ribs， the plate strips were capable of developing post-buckling strength； however， the tensile effect induced by the formation of local tension fields ultimately led to flexural-torsional instability of the ribs， resulting in overall failure. The shear resistance of DPS-V was primarily provided by the plate strips， whereas that of DPS-D was derived from the combined action of the plate strips and ribs， exhibiting significant anisotropic behavior—its bearing capacity under diagonal tension was 38% higher than that under diagonal compression. Although the initial stiffness and ultimate bearing capacity of DPS-V were slightly lower than those of DPS-D， DPS-V demonstrated superior ductility and deformability beyond the peak load. Based on the superposition principle， design formulas for predicting the shear capacity of the two types of steel sheets were proposed. The relative error between the calculated and experimental values was within 4%， providing a reliable reference for the engineering design of such components.

The Shenzhen local standard， Technical Standard for Green Demolition of Buildings， was issued and implemented on January 31， 2025， by the Shenzhen Municipal Standards Committee. Based on this newly compiled standard， the definition， framework， application objectives， and demolition technologies for green demolition were analyzed； the current development status of building demolition methods was summarized and evaluated； and the principles for preparing a special green demolition scheme， which balances the goals of structural dismantling safety and comprehensive utilization of demolition waste， were elaborated. Furthermore， a practical application of the standard was carried out in a building demolition project in the Xinqiao East Area urban renewal project in Shenzhen. The results showed that the technical guidelines established in the standard enabled classified and orderly demolition of existing buildings， leading to classified and graded comprehensive utilization of demolition waste. This achieved an on-site utilization rate of 30% and a comprehensive utilization rate of 100% for the demolition waste， thereby improving the comprehensive utilization level and resource recovery efficiency of the project’s demolition waste. This established a technical paradigm for green demolition of buildings and provided a basis for the promotion and application of green demolition technologies.

To address the low efficiency， high risk， and limited quantitative capability of manual inspection for fatigue cracks in steel box girders， a study was conducted on the force analysis and motion control of a magnetic wall-climbing robot for crack inspection. According to the crack inspection requirements for deck plates and diaphragms， a wall-climbing robot equipped with an eddy current testing device was designed， and key parameters including overall dimensions， payload capacity， and operating speed were determined. Static and dynamic models of the robot were established to analyze the minimum magnetic adhesion force and driving torque required on steel plate surfaces. Based on the Webots platform， simulations were carried out to investigate the robot’s motion under different payload and weld obstacle conditions. The results showed that the robot could move continuously between the diaphragm and deck plate. As the payload increased， the start-up time on the diaphragm became longer and speed fluctuation became more pronounced， while the motion on the deck plate remained relatively stable. When crossing a weld， short-term speed fluctuations occurred， and the pitch angle increased significantly with the rising payload. Overall， the robot still maintained good obstacle-crossing capability and motion stability.

Aiming at the problems of low efficiency， strong reliance on manual labor， high risk of high-altitude work， and secondary damage that is easily caused by contact detection in traditional methods for building exterior wall disease detection， this paper proposes an intelligent non-destructive detection method based on machine vision and deep learning. This method enables rapid identification of three types of apparent diseases： spalling， hollowing， and cracking. Using UAV high-precision collection equipment， disease images were collected from typical exterior wall types such as tiles， paint， and cement mortar. A building exterior wall disease image database containing 1018 images of three types of diseases was constructed. Through LabelMe software， disease annotation was performed， forming 1168 spalling labels， 1619 hollowing labels， and 1515 cracking labels. Based on the deep learning YOLO11n model， multiple training schemes were implemented on the training set. This study found that， with 300 training epochs， an image size of 1280 pixels， and data augmentation enabled， a detection performance of mAP50 = 0.753 was achieved. This model relatively accurately identified the three types of apparent diseases： spalling， hollowing， and cracking. Finally， engineering instance applications were carried out in multiple residential communities in the Chengdu area， further proving that the model has good generalization ability and can provide a new technology for non-destructive rapid detection of building exterior wall diseases.

The Red Mansion at No. 106 Huangpu Road， Shanghai， was constructed in 1911. It is a three-story brick-wood structure. In its comprehensive protective renovation project， three major challenges were encountered： the simultaneous construction of a complex group of adjacent deep foundation pits， the overall ultra-high jacking by 6.55 m to restore its historical appearance， and the synchronous development of underground space together with the improvement of the building’s seismic performance. To address these challenges， a complete set of key techniques was proposed， integrating underpinning， active deformation control， synchronous high-position jacking， and seismic isolation with story addition. Using an adjustable active underpinning system， the cumulative additional deformation of the Red Mansion during the construction of the surrounding deep foundation pits was controlled within ±5 mm. A relay lifting technique combining "lifting + jacking" was adopted to achieve the ultra-high jacking of 6.55 m， along with the simultaneous high-position rectification of 300 mm. The addition of a seismic isolation layer significantly enhanced the structural seismic performance. After three rounds of whole-process load transfer， the maximum inclination ratio of the building foundation was reduced from the initial 9.12‰ to below 2.5‰， with no new structural cracks generated. This project realized the in-situ preservation， jacking with story addition， and functional upgrading of an outstanding historical building in Shanghai under the condition of simultaneous construction adjacent to a group of deep foundation pits， setting a record for the highest overall jacking height of modern outstanding historical buildings in China.

Many existing rural houses face structural safety hazards due to material performance degradation. This study investigated the residual bearing capacity and the strengthening effect of carbon fiber reinforced polymer （CFRP） sheets on old precast prestressed concrete （PC） hollow-core slabs， using specimens obtained from a demolished 45-year-old rural house in Shanghai. The test involved two PC slabs： one served as the control specimen， and the other was strengthened with CFRP sheets. Static loading tests were conducted to compare and analyze their failure modes， deformation capacity， and energy dissipation capacity. Based on the measured data， the strain development pattern of the CFRP sheets was analyzed. The results showed that the 45-year-old PC hollow-core slabs still had a certain bearing capacity but with a low safety margin， exhibiting a typical brittle flexural failure due to under-reinforcement. After CFRP strengthening， the failure mode changed to shear failure with obvious ductile characteristics， because the CFRP sheets bore the main tensile stress in the later loading stage.

The external thermal insulation composite system （ETICS） is crucial for improving building energy efficiency and ensuring building functionality. In recent years， issues such as cracking， hollowing， peeling， and high-altitude falling have occurred frequently， posing a significant threat to public safety. A systematic review was conducted on domestic and international research and engineering practice regarding diagnosis and treatment methods for detection， evaluation， and repair of building ETICS. In terms of detection， non-destructive testing techniques were categorized into four types based on their energy forms and physical mechanisms， namely optical， thermal， electromagnetic， and acoustic. The research progress of various non-destructive testing techniques and commonly used destructive testing techniques was systematically reviewed. A comparative analysis was conducted on the technical points， advantages and disadvantages， and applicable scenarios of various detection techniques. In terms of evaluation， the characteristics and progress of existing evaluation methods were summarized from three aspects： qualitative evaluation， quantitative evaluation， and comprehensive evaluation. In terms of repair， the current development status of existing repair methods was introduced from the perspectives of repair technology， repair materials， and repair strategies. Finally， the deficiencies in the research and engineering practice regarding diagnosis and treatment methods for building ETICS were analyzed， and future research directions were discussed.